The present invention relates to a direction detecting system for generating a direction signal corresponding to the direction of movement of a moving body such as a motor vehicle in response to a signal from a geomagnetic field sensor.
In conventional direction detecting systems, the distortion of the earth magnetism due to the residual magnetism of the vehicle or the like is corrected by a correcting magnet mounted on the outside of the vehicle.
This prior art construction requires consideration of various factors including the position, number and the intensity of the correcting magnet mounted on the vehicle for offsetting the distortion of the earth magnetism due to the residual magnetism of the vehicle or the like. Partly due to the complicated procedures of correction and partly due to the difference of the distortion characteristics of the earth magnetism for different vehicles, different corrections are required for different vehicles. Further, since the signal from the earth magnetism sensor itself is distorted in some cases, the accurate detection of the direction of the earth magnetism is impossible by the prior art systems.